Rainbow Dash was a very proud pony. She was proud of her flying skills, she was proud of her pranking, she was proud through and through. When Twilight made an attempt to prank her back something went spectacularly wrong.
 
As Rainbow Dash grew bigger and bigger so her pride became hubris. Every time she spoke her tone was patronising. Before long she promptly scooped Ponyville up in her hoof without so much as a by-your-leave and took earth-shaking steps towards Canterlot.
 
“Hey, Princess.” Her voice rang through the whole city. “I think we might need to consider a new title for yours truly.”